The prior art contains many examples of devices for conveying or spraying insulation, ashes, slurries and the like, by pneumatic means. Many are of the jet suction or jet assisted type, wherein jets of a liquid or gas under pressure are introduced into a stream of the material being conveyed, or are used at the terminus to create suction of the material. These types of devices function effectively so long as the material being conveyed is not effected by sudden increases in pressure or turbulence, or so long as it is not important that the structural integrity of the material be preserved, as in the case of ash conveyors. But certain of the newer particulate insulation materials, for example, Dacotherm.RTM., have presented a problem. The conventional means of delivery by hose until the present have proven unfeasible as such means tend to disintegrate and powder the material excessively.